SeismicarchitectureofaLowerCretaceousplatform-to-slopesystem,SantaAguedaandPozaRicafields,MexicoXavierJanson,CharlesKerans,RobertLoucks,M.AlfredoMarhx,CarlosReyes,andFranciscoMurguiaABSTRACT

Twothree-dimensionalseismicdatasetsovertheAlbianwest-ernGoldenLanemarginandtime-equivalentbasinaldepositsofPozaRicafieldallowedustoinvestigatethelinkedarchitec-tureofasteep-sidedcarbonateplatform(ElAbraFormation)andathickaccumulationofredepositedcarbonatesedimentatthetoeoftheslopeandinthebasinalarea(TamabraForma-tion).Regionalseismiccrosssectionsshowthatthemostag-gradingAlbianplatformhasanerodedplatformtop,ascal-lopedmargin,andachannelizedslopethatareequivalenttoa20-km(12.4-mi)-wide,westward-thinning,thicktoe-of-slopeapronmadeofchaotic,contorted,mounded,moderate-tohigh-amplitudereflections.DetailedreflectiongeometriesintheAlbiantoe-of-slopeandbasinaldepositsconsistofchaotictoshort,discontinuous,low-amplitudereflectionatthetoeoftheslopeoftheGoldenLaneplatform,laterallychangingtoadis-continuousmounded,shinglingreflection,whichultimatelyturnsintohigh-amplitudeparallelreflections.Weinterpretthislateralchangetoreflecttheseismicsignatureofthechangefromtheblock-anddebris-flow–dominatedtoe-of-slopearea,todebris-flowandconcentrateddensityflowdepositsinthebasinthatultimatelygradelaterallyintopelagicdeposits.Onaflattenedseismicslice,moundedreflectionscorrespondtolo-batetofan-shapedseismiceventsseveralkilometerswidethatareinterpretedasacarbonatebasin-floorfan.Comparisonbe-tweencoreandseismicdatashowsadominanceofdebrisflowsinthelowertwoAlbiansequences(Albian1andAlbian2)thatgradeverticallyintomorelobateconcentrateddensityflowsCopyright?2011.TheAmericanAssociationofPetroleumGeologists.Allrightsreserved.ManuscriptreceivedJuly6,2009;provisionalacceptanceOctober29,2009;revisedmanuscriptreceivedMarch17,2010;finalacceptanceJune30,2010.

DOI:10.1306/06301009107

AAPGBulletin,v.95,no.1(January2011),pp.105–146105AUTHORSXavierJanson??BureauofEconomicGe-ology,UniversityofTexasatAustin,UniversityStationBoxX,Austin,Texas78713-8924;xavier.janson@beg.utexas.eduXavierJansonreceivedhisPh.D.fromtheUni-versityofMiamiin2002,wherehewasastudentintheComparativeSedimentologyLaboratory.HereceivedaD.E.A.degree(equivalenttoanM.Sc.degree)fromtheInstitutFran?aisduPétrole.HejoinedtheReservoirCharacteriza-tionResearchLaboratoryattheBureauofEco-nomicGeologyoftheJacksonSchoolofGeo-sciencesattheUniversityofTexasatAustinin2002,wherehiscurrentresearchinvolvesbuilding3-Dgeocellularmodelsand3-Dsyn-theticseismicmodelsfromoutcropstudytohelpreservoircharacterizationandseismicinterpretation.CharlesKerans??DepartmentofGeologicalSciences,UniversityofTexasatAustinUniver-sityStationC1100Austin,Texas78712-0254CharlieKeransiscurrentlytheGoldhammerChairofCarbonateGeologyattheDepartmentofGeologicalSciences,JacksonSchoolofGeo-sciences,UniversityofTexasatAustin.Upuntil2005,hewasaseniorresearchscientistattheBureauofEconomicGeologyattheUniversityofTexas,wherehehadworkedsince1985.Hisareasoffocusareincarbonatesequencestra-tigraphyandreservoircharacterization,withanemphasisonintegratingoutcropanalogin-formationforimprovedunderstandingofthesubsurface.KeransreceivedhisPh.D.fromCarletonUniversityinOttawa,Canada,in1982,wherehestudiedbasinanalysisandtheoriginofPrecambriancarbonates.KeransheldaWesternAustralianMiningandPetroleumRe-searchInstitutepostdoctoralfellowshipbe-tween1982and1985,studyingDevonianreefcomplexesoftheCanningBasinunderPhilipPlayfordoftheWesternAustralianGeologicalSurvey.In1985,KeranstookapositionattheBureauofEconomicGeology,whereheinitiatedtheCarbonateReservoirCharacterizationRe-searchLaboratoryattheBureauin1988andhascodirectedthisresearcheffortwithJerryLuciaoftheBureauuptothepresent.KeranshasbeenbothadomesticandinternationalAAPGdistinguishedlecturer.HealsowonthePratt

AwardfromAAPGforbestarticleintheAAPGBulletinin1994(firstauthor)andin2005(secondauthor).

RobertLoucks??BureauofEconomicGe-ology,UniversityofTexasatAustin,UniversityStationBoxX,Austin,Texas78713-8924

RobertG.LoucksisaseniorresearchscientistattheBureauofEconomicGeology.HereceivedhisB.A.degreefromtheStateUniversityofNewYorkatBinghamtonin1967andhisPh.D.fromtheUniversityofTexasatAustinin1976.Hisgeneralresearchinterestsincludecarbonateandsiliciclasticsequencestratigraphy,depo-sitionalsystems,diagenesis,andreservoircharacterization.

M.AlfredoMarhx??PemexExploracionyProduccion,PozaRica,Mexico

AlfredoMarhx-Rojano,receivedhisM.I.degreefromtheNationalUniversityofMexico(UNAM)in2010,wherehestudiedenergeticsubsurfaceresources;hereceivedhisbachelor’sfromNa-tionalPolytechnicInstitutein1981,withanemphasisonsurfacegeologicalstudiesfromSantaCatarinaS.L.P.Mexico.HejoinedPetróleosMexicanos(PEMEX)in1983.Hisprofessionaldevelopmentincludessurfaceandsubsurfacegeology,sedimentologyandstratigraphicstudies,andreservoirdevelopmentstudies.CarlosReyes??PemexExploracionyPro-duccion,PozaRica,Mexico

CarlosA.ReyesLópezstudiedhisM.I.degreefromtheNationalUniversityofMexico(UNAM)between1986and1989,wherehewasastu-dentofphysicsofreservoirs;receivedhisbach-elorsfromUNAMin1982,withthe“AirandFoamDrilling.”HejoinedPetróleosMexicanos(PEMEX)in1983.Hisprofessionaldevelopmentincludessurfaceandsubsurfacereservoiren-gineeringstudies,andhehasbeenteamleaderseveraltimesinonshoreandoffshoreprojects.FranciscoMurguia??PemexExploracionyProduccion,PozaRica,Mexico

FranciscoMurguiaisaseismicinterpreterandiscurrentlyinchargeoftherepresentationofinfor-mationtechnologiesinthePozaRica–AltamiraAssetofPEMEXExplorationandProduction.HeiscertifiedinLandmarkinteractiveinterpretationsystems,withgreatexperienceintheuseofIn-ternetandintranettechnologiesforaccessofdatainthedatabase,andtheapplicationforthe

106andturbiditesintheuppertwoAlbiansequences(Albian3andAlbian4).Seismicdatausedinthisstudy,combinedwithcoreobservations,donotsupporttheinterpretationoftheAlbianTamabraFormationbeingofshallow-waterorigin.Seismicfea-turesidentifiedasbasin-floorfan,channel,anddebris-flowde-positshaveashapeandsizethataresimilartothoseofotherredepositedbasinalcarbonatedepositselsewhere.TheseismicarchitectureshowsthatthePozaRicafieldisatypicalexampleofthickaccumulationofgrainyporouscarbonatedepositsinabasinalsetting.Thisexampleshowsthepotentialofalargehy-drocarbonaccumulationinatectonicallymodifiedstratigraphictraparoundshallow-watercarbonateplatforms.INTRODUCTIONTheeasternGoldenLaneplatforminCentralMexicoanditsassociatedthickbasinaldebrisapronhavebeenidentifiedsinceitsearlyoildiscoveryinthe1930s(BarnetcheandIlling,1956;ViniegraandCastillo-Tejero,1970;Cooganetal.,1972;Enos,1977;Wilson,1990;McFarlanandMenes,1991;Goldhammer,1999).PozaRicafield,whichproducesfromtheAlbianTamabraFormation(Salas,1949),isconsideredaclassicexampleofathickaccumulationofredepositedcarbonatesedimentadja-centtoahigh-reliefshallow-watercarbonateplatform.BecauseofthePozaRicaoilfield,three-dimensional(3-D)and2-Dseis-micwelllogsandcoreareavailablefordetailedstudyofthearchitectureofthelinkedplatform,slope,andbasinaldeposi-tionalenvironment.BecauselittleoilorgasproductionispresentoutsidetheAlbianofMexicoorthePermianofwestTexasfromredepositeddeep-watercarbonatedeposits,theyhavereceivedlesserattentionthantheirsiliciclasticcounterparts.Combining3-DseismicdataovertheGoldenLaneplat-formandtime-equivalentbasinaldepositsofPozaRicafield,aswellasintegratingwellandcoredata,hasallowedustoanalyzetheseismicarchitectureofashallow-watercarbonate-platformtop,theplatformmargin,andtheassociatedsteepbypassslope,alongwiththetime-equivalenttoe-of-slopebasinalapronofredepositedcarbonate.The3-Dseismicdatarevealnotonlythestratigraphicarchitectureofvariousredepositedsedimen-tarybodies,butalsotheirrelativepositionsalongthedeposi-tionalprofile,theirdimensions,andtheirmorphology.Followingabriefregionalgeologicintroduction,aswellasashortdescriptionofthedataandmethodsusedinthisstudy,thisarticlediscusses,first,theseismicarchitectureofaplatform,slope,andbasinobservedinacompositeregionalseismicprofile.SeismicArchitecture,SantaAguedaandPozaRicaFields,Mexico

Second,theseismicarchitectureandmorphologyoftheplat-formtopandslopewillbedescribedonthebasisofa3-DseismicdatasetovertheSantaAguedafieldontheGoldenLaneplat-form.Finally,usingasecond3-DdatasetoverthePozaRicafield,wewillinvestigatetheseismicexpressionofredepositedcarbonateinthetoe-of-slopeandbasinalareausingdetailedreflectiongeometries,isochoremaps,andseismicattributeslices,aswellasseismic-sectionandwell-logandcore-cross-sectioncomparison.